"I want to say Happy Mother's Day to the moms in my life: my mom Chris and my amazing wife Jennifer, who is an incredible, spectacular, world-class mom," he says in a video, which advocates for those raising children in the Democratic Republic of the Congo, another display of his ardent activism for the African country.

Being a mother is "the hardest job that there is, every single day," Affleck, 39, adds, also giving a nod to the women he met in the Congo. (He founded the Eastern Congo Initiative nonprofit in 2010.)

And that's more than a 9-5 job for Garner: In February, the couple welcomed a son, Samuel, who joined big sisters Seraphina, 3, and Violet, 6.